Using two-dimensional solar images at 73.8 MHz, obtained with the Clark Lake Multifrequency Radioheliograph, we present direct evidence that type III electron streams propagate in dense coronal streamers. This evidence is substantiated by the excellent coincidence that we find in position angle between the densest parts of streamers observed with the Solwind coronagraph on the P78-1 satellite and the maximum brightness of type III burst sources.